1. Field of the Invention
The present invention relates to a passenger detecting system, a passenger detecting method and an air bag system using the same. More particularly, the present invention relates to the technique for detecting an existence or non-existence of a passenger in a passenger seat in an automobile and for controlling the expansion of an air bag in an air bag system based on the detection result.
2. Description of the Related Art
Generally, an air bag system is a system to protect a driver of an automobile from the impact when an automobile collides. Recently, the air bag system is installed for a passenger in addition to a driver. Thus, even if the automobile collides, the passenger on the passenger seat can be protected from the impact on the collision by the expanding operation of the air bag in addition to the driver.
As shown in FIG. 1, an air bag system is composed of a squib circuit on the side of a driver seat, a squib circuit on the side of a passenger seat, an electronic acceleration sensor (a collision detecting sensor) GS and a control circuit CC. The squib circuit on the side of the driver seat is composed of a series circuit of a safing sensor SS1, a squib SQ1, and a semiconductor switching element SW1 such as a field effect transistor. The squib circuit on the side of the passenger seat is composed of a series circuit of a safing sensor SS2, a squib SQ2, and a semiconductor switching element SW2 of a field effect transistor. The control circuit CC detects collision in response to an output signal of the electronic acceleration sensor GS and supplies detection signals to the gates of the semiconductor switching elements SW1 and SW2.
According to the air bag system, when the automobile collides because of any cause, the switch contacts of the safing sensors SS1 and SS2 respond to the relatively small acceleration to be closed. The squib circuit on the side of the driver seat and the squib circuit on the side of the passenger seat are set to the operable state. When the control circuit CC determines the collision of the automobile in response to an acceleration detection signal from the electronic acceleration sensor GS, the control circuit CC supplies the detection signals to the gates of the semiconductor switching elements SW1 and SW2. As a result, the switching elements SW1 and SW2 are set to the ON state. Thus, current flows through each squib circuit. In this way, the air bag on the side of the driver seat and the air bag on the side of the passenger seat are expanded because of heat generation by the squibs SQ1 and SQ2 to protect the driver and the passenger from the impact due to the collision.
By the way, in this air bag system, an air bag is expanded irrespective of existence or non-existence of the passenger on the passenger seat, when the automobile collides. Therefore, when the passenger has sat on the passenger seat, the protection effect of the passenger can be expected upon the collision. In this case, however, when the passenger is not on the passenger seat, the expansion of the air bag does not have any meaning and a repair expenses to restore the air bag becomes necessary. Therefore, it is preferable that a passenger detecting system determines whether or not a passenger is on the passenger seat, and the expansion operation of the air bag system is performed upon the collision, only when the passenger is on the passenger seat.
In order to solve the above problem, an air bag system as shown in FIG. 2 is proposed. In the air bag system shown in FIG. 2, a sensor SD is provided to determine whether or not a passenger is on the passenger seat, and the control circuit CC determines that the passenger is on the passenger seat, based on a detection signal of the sensor SD. Thus, an air bag is set to an either of the expansion allowed state in which it is expanded when the automobile collides or the expansion inhibited state in which it is not expanded even when the automobile collides.
As the passenger detecting system to detect the existence or non-existence of the passenger on the passenger seat are proposed various systems. In Japanese Laid Open Patent Application (JP-A-Heisei 4-46843), Japanese Laid Open Utility Model Application (JP-U-Heisei 3-52266), Japanese Laid Open Patent Application (JP-A-Showa 61-113527), a passenger detecting system in which a weight sensor is incorporated inside the seat is disclosed. Also, in Japanese Laid Open Patent Application (JP-A-Heisei 9-509118), a passenger detecting system in which electrodes are arranged in a seat section and a back supporting section of a seat and an oscillation circuit is connected between the electrodes or between the electrode and the chassis of a vehicle.
According to the former passenger detecting system, the weight sensor does not respond when anybody or anyone is not on the passenger seat. Thus, the existence or non-existence of the passenger on the passenger seat can be detected by the weight sensor. Also, according to the latter passenger detecting system, a capacitance increases between the electrodes or between the electrode and the chassis of the automobile when the passenger is on the seat. The passenger detecting system using the weight sensor is possible to perform the rough determination of whether the passenger on the passenger seat is an adult or a child. An air bag is set to either of the expansion allowed state or the expansion inhibited state, based on the determination result. Thus, an unexpected situation upon the collision of the automobile can be avoided. However, the weights are quite different between individuals and a child can be sometimes heavier than an adult. Therefore, the passenger detecting system using the weight sensor lacks of accuracy.
On the other hand, the capacitance decreases when any passenger is not on the passenger seat. The change of an oscillation frequency due to the change of the capacitance is detected using this phenomenon and the existence or non-existence of the passenger on the passenger seat can be detected. Also, when the passenger is not on the passenger seat, the expansion operation of the air bag system can be prevented, unlike the conventional air bag system. However, the electrode 4 is connected to a cable 106 using a connector 110. Therefore, there is a problem that the work efficiency is low and the reliability is low.
In addition to the technique using a sensor detecting the weight of a passenger, there is known the technique in which the passenger is picked up by a camera and determinations of whether the existence or non-existence of the passenger is on the passenger seat, and whether the passenger is a adult or a child are performed through an image processing. Thus, in case of the passenger detecting system using a camera, the existence or non-existence of the passenger, and the adult or the child can be quite correctly determined. However, because a passenger pattern must be determined from various data obtained by processing the imaging data which has been taken by the camera, a processor becomes complicated and expensive.
Therefore, an object of the present invention is to provide a passenger detecting system and a passenger detecting method which can detect the existence or non-existence of a passenger on a passenger seat accurately without being too much influenced by a wear, the figure and the attitude of the passenger.
Another object of the present invention is to provide a passenger detecting system and a passenger detecting method, which can accurately detect whether the passenger is an adult or a child.
Still another object of the present invention is to provide a passenger detecting system using an electrode connection structure formed such that a cable can be connected with antenna electrodes formed on a base member.
Yet still another object of the present invention is to provide an air bag system which includes either of the above passenger detecting systems and in which the expansion of an air bag can be controlled based on a detecting result of the passenger detecting system.
In order to achieve an aspect of the present invention, a passenger detecting system includes a plurality of antenna electrodes provided in a seat, a signal generating section, a detecting section, a switching circuit and a control unit. The signal generating section generates an electrode signal. The switching circuit sequentially supplies the electrode signal to the plurality of antenna electrodes one by one in response to a switching control signal. The detecting section detects change of the electrode signal to generate a detection signal when the electrode signal is supplied to each of the plurality of antenna electrodes. The control unit outputs the switching control signal to the switching circuit and generates a passenger data associated with a passenger on the seat based on the detection signal for each of the plurality of antenna electrodes.
The passenger detecting system may further include an amplitude detecting circuit detecting an amplitude of the electrode signal, and an amplitude control circuit adjusting the amplitude of the electrode signal to a predetermined value in response to an amplitude control signal. The control unit outputs the amplitude control signal to the amplitude control circuit based on the detected amplitude of the electrode signal by the amplitude detecting circuit.
The passenger data preferably includes a first data indicative of existence or non-existence of the passenger on the seat. Also, it is preferable that the passenger data further includes a second data indicative of whether or not the passenger is a child or an adult.
The control unit may calculate a summation of the detection signals for the plurality of antenna electrodes, and determine whether the passenger exists on the seat, based on the summation to generate the passenger data. In this case, when it is determined that the passenger exists on the seat, the control unit may calculate a ratio data of each of the detection signals to the summation, and determine whether the passenger is a child or an adult, based on a distribution pattern of the radio data of the detection signals, to generate the passenger data. Instead, when it is determined that the passenger exists on the seat, the control unit may calculate a ratio data of each of the detection signals to the summation, determine the ratio data corresponding to a head of the passenger, calculate a second summation of the ratio data of the detection signals other than the ratio data corresponding to the head, and determine whether the passenger is a child or an adult, based on the second summation, to generate the passenger data.
The detecting section may further detect a phase difference before and after the change of the electrode signal. The control unit determines whether the passenger exists on the seat, based on the phase difference, to generate the passenger data. In this case, when it is determined that the passenger exists on the seat, the control unit may detect one of the plurality of antenna electrodes corresponding to a position of a shoulder of the passenger, based on the detection signals, and determine whether the passenger is a child or an adult, based on the detected antenna electrode, to generate the passenger data.
It is preferable that the plurality of antenna electrodes are dispersedly provided in the seat. The plurality of antenna electrodes may be provided to extend in a horizontal direction and to be apart from each other in a vertical direction. Also, each of the plurality of antenna electrodes may be a metal plate. Instead, each of the plurality of antenna electrodes may be an electrically conductive portion of an insulation cloth. Instead, each of the plurality of antenna electrodes may be a portion of an insulation cloth in which an electrically conductive paint is painted. Instead, each of the plurality of antenna electrodes may be a portion of an insulation cloth in which metal threads are woven.
Each of the antenna electrodes is connected to the switching circuit by use of a cable, and the cable has a washer having a peripheral section and a plurality of portions extending from the peripheral section into a direction of a center portion. In this case, a fixture has a first section of a first diameter, a second section of a second diameter on the first section, the second diameter being smaller than the first diameter, and a third section of a third diameter on the second section, the third diameter being larger than the first diameter, and the fixture is pushed and inserted to pass through a base member, the antenna electrode and the center portion of the washer such that the base member and the antenna electrode are sandwiched by the third section of the fixture and the peripheral section of the washer through an elastic force of the plurality of portions of the washer. In this case, each antenna electrode is turned at an edge portion of the base member, and the washer is electrically conductive.
In order to achieve another aspect of the present invention a method of detecting a passenger in an automobile, include:
sequentially supplying an electrode signal to a plurality of antenna electrodes one by one, the plurality of antenna electrodes being provided in a seat;
detecting change of the electrode signal to generate a detection signal when the electrode signal is supplied to each of the plurality of antenna electrodes; and
generating a passenger data associated with a passenger on the seat based on the detection signal for each of the plurality of antenna electrodes.
The method may further include:
detecting an amplitude of the electrode signal; and
adjusting the amplitude of the electrode signal to a predetermined value based on the detected amplitude of the electrode signal.
The generating a passenger data may includes determining whether the passenger is on the seat, and whether the passenger is a child or an adult, based on a distribution pattern of the detection signals.
The generating a passenger data may includes:
calculating a summation of the detection signals for the plurality of antenna electrodes; and
determining whether the passenger exists on the seat, based on the summation to generate the passenger data. In this case, the generating a passenger data may include:
calculating a ratio data of each of the detection signals to the summation, when it is determined that the passenger exists on the seat; and
determining whether the passenger is a child or an adult, based on a distribution pattern of the radio data of the detection signals, to generate the passenger data.
Also, the generating a passenger data may include:
calculating a ratio data of each of the detection signals to the summation, when it is determined that the passenger exists on the seat;
determining the ratio data corresponding to a head of the passenger;
calculating a second summation of the ratio data of the detection signals other than the ratio data corresponding to the head; and
determining whether the passenger is a child or an adult, based on a distribution pattern of the radio data of the detection signals, to generate the passenger data.
The method may further include detecting a phase difference before and after the change of the electrode signal. At this time, the generating a passenger data includes determining whether the passenger exists on the seat, based on the phase difference, to generate the passenger data. In this case, the generating a passenger data may include:
detecting one of the plurality of antenna electrodes corresponding to a position of a shoulder of the passenger, based on the detection signals, when it is determined that the passenger exists on the seat; and
determining whether the passenger is a child or an adult, based on the detected antenna electrode, to generate the passenger data.
In order to achieve another aspect of the present invention, a passenger detecting system include a plurality of antenna electrodes provided in a seat, a detecting section and a control unit. The detecting section detects change of an electric field intensity around each of the plurality of antenna electrodes to generate a detection signal. The control unit generates a passenger data associated with a passenger on the seat based on the detection signal for each of the plurality of antenna electrodes.
The passenger data preferably includes a first data indicative of existence or non-existence of the passenger on the seat, and a second data indicative of whether or not the passenger is a child or an adult.
Also, it is preferably that the plurality of antenna electrodes are dispersedly provided in the seat. In this case, the plurality of antenna electrodes may be provided to extend in a horizontal direction and to be apart from each other in a vertical direction. Each of the plurality of antenna electrodes may be a metal plate. Instead, each of the plurality of antenna electrodes may be an electrically conductive portion of an insulation cloth. Instead, each of the plurality of antenna electrodes may be a portion of an insulation cloth in which an electrically conductive paint is painted. Instead, each of the plurality of antenna electrodes may be a portion of an insulation cloth in which metal threads are woven.
In order to achieve another aspect of the present invention, an air bag system with a passenger detecting system include a plurality of antenna electrodes, a detecting section, a control unit, an air bag and an air bag control unit. The plurality of antenna electrodes are provided in a seat. The detecting section detects change of an electric field intensity around each of the plurality of antenna electrodes to generate a detection signal. The control unit generates a passenger data associated with a passenger on the seat based on the detection signal for each of the plurality of antenna electrodes. Then air bag control unit controls the air bag such that the air bag is selectively expanded based on the passenger data.
The air bag system may further include a signal generating section generating an electrode signal, and a switching circuit sequentially supplying the electrode signal to the plurality of antenna electrodes one by one in response to a switching control signal such that an electric field is generated around the plurality of antenna electrodes. At this time, the control unit outputs the switching control signal to the switching circuit.
Also, the air bag system may further include an amplitude detecting circuit detecting an amplitude of the electrode signal, and an amplitude control circuit adjusting the amplitude of the electrode signal to a predetermined value in response to an amplitude control signal. At this time, the control unit outputs the amplitude control signal to the amplitude control circuit based on the detected amplitude of the electrode signal by the amplitude detecting circuit.
The passenger data may include a first data indicative of existence or non-existence of the passenger on the seat. At this time, when the passenger data indicates non-existence of the passenger, the air bag control unit controls the air bag such that the air bag is not expanded.
Also, the passenger data may include a second data indicative of whether or not the passenger is a child or an adult. At this time, when the passenger data indicates that the passenger is the child, the air bag control unit controls the air bag such that the air bag is not expanded.
The control unit may calculate a summation of the detection signals for the plurality of antenna electrodes, and determine whether the passenger exists on the seat, based on the summation to generate the passenger data. In this case, when it is determined that the passenger exists on the seat, the control unit may calculate a ratio data of each of the detection signals to the summation, and determine whether the passenger is a child or an adult, based on a distribution pattern of the radio data of the detection signals, to generate the passenger data. Also, when it is determined that the passenger exists on the seat, the control unit may calculate a ratio data of each of the detection signals to the summation, determine the ratio data corresponding to a head of the passenger, calculate a second summation of the ratio data of the detection signals other than the ratio data corresponding to the head, and determine whether the passenger is a child or an adult, based on the second summation, to generate the passenger data.
Also, the air bag system may further include a phase difference detecting section detecting a phase difference in a displacement current before and after the change of the electric intensity de signal. At this time, the control unit determines whether the passenger exists on the seat, based on the phase difference, to generate the passenger data. In this case, when it is determined that the passenger exists on the seat, the control unit may detect one of the plurality of antenna electrodes corresponding to a position of a shoulder of the passenger, based on the detection signals, and determine whether the passenger is a child or an adult, based on the detected antenna electrode, to generate the passenger data.
The plurality of antenna electrodes may be dispersedly provided in the seat. In this case, the plurality of antenna electrodes may be provided to extend in a horizontal direction and to be apart from each other in a vertical direction. Instead, each of the plurality of antenna electrodes may be a metal plate. Instead, each of the plurality of antenna electrodes may be an electrically conductive portion of an insulation cloth. Instead, each of the plurality of antenna electrodes may be a portion of an insulation cloth in which an electrically conductive paint is painted. Instead, each of the plurality of antenna electrodes may be a portion of an insulation cloth in which metal threads are woven.
When each of the antenna electrodes is connected to the switching circuit by use of a cable, and when the cable has a washer having a peripheral section and a plurality of portions extending from the peripheral section into a direction of a center portion, a fixture preferably has a first section of a first diameter, a second section of a second diameter on the first section, the second diameter being smaller than the first diameter, and a third section of a third diameter on the second section, the third diameter being larger than the first diameter. The fixture is preferably pushed and inserted to pass through a base member, the antenna electrode and the center portion of the washer such that the base member and the antenna electrode are sandwiched by the third section of the fixture and the peripheral section of the washer through an elastic force of the plurality of portions of the washer. In this case, the antenna electrode is turned at an edge portion of the base member, and the washer is electrically conductive.
In order to achieve another aspect of the present invention, a method of controlling expansion of an air bag in an automobile, include:
sequentially supplying an electrode signal to a plurality of antenna electrodes one by one, the plurality of antenna electrodes being provided in a seat;
detecting change of the electrode signal to generate a detection signal when the electrode signal is supplied to each of the plurality of antenna electrodes;
generating a passenger data associated with a passenger on the seat based on the detection signal for each of the plurality of antenna electrodes;
controlling an air bag based on the passenger data such that the air bag is selectively expanded.
The method may further include:
detecting an amplitude of the electrode signal; and
adjusting the amplitude of the electrode signal to a predetermined value based on the detected amplitude of the electrode signal.
Also, the controlling an air bag includes:
allowing expansion of the air bag when it is determined that the passenger is on the seat and that the passenger is an adult; and
inhibiting the expansion of the air bag when it is determined that the passenger is not on the seat or that the passenger is a child.
The generating a passenger data may include determining whether the passenger is on the seat, and whether the passenger is a child or an adult, based on a distribution pattern of the detection signals. Otherwise, the generating a passenger data may include:
calculating a summation of the detection signals for the plurality of antenna electrodes; and
determining whether the passenger exists on the seat, based on the summation to generate the passenger data. In this case, the generating a passenger data includes:
calculating a ratio data of each of the detection signals to the summation, when it is determined that the passenger exists on the seat; and
determining whether the passenger is a child or an adult, based on a distribution pattern of the radio data of the detection signals, to generate the passenger data.
Also, the generating a passenger data may include:
calculating a ratio data of each of the detection signals to the summation, when it is determined that the passenger exists on the seat;
determining the ratio data corresponding to a head of the passenger;
calculating a second summation of the ratio data of the detection signals other than the ratio data corresponding to the head; and
determining whether the passenger is a child or an adult, based on a distribution pattern of the radio data of the detection signals, to generate the passenger data.
The method may further include detecting a phase difference before and after the change of the electrode signal, and
the generating a passenger data includes determining whether the passenger exists on the seat, based on the phase difference, to generate the passenger data.
Also, the generating a passenger data may include:
detecting one of the plurality of antenna electrodes corresponding to a position of a shoulder of the passenger, based on the detection signals, when it is determined that the passenger exists on the seat; and
determining whether the passenger is a child or an adult, based on the detected antenna electrode, to generate the passenger data.